For example, there is a technology of creating a three-dimensional model of a building and allowing for movement (walk-through) in the three-dimensional model. A user can move a camera (viewpoint), for example, by mouse operation. It is possible to simulate the movement in the building on a computer, which is useful for checking the usability of the building in a design phase or the like, for example.
Also, there has been proposed a technology of setting a traffic line in section link information indicating the connection relation of sections that constitute a floor plan (for example, Patent document 1). Pass-through sections and portals (gateways) on the way from the current position to a destination position are searched by tracing the connection relation of sections and portals alternately by referring to a portal connected with a section and further referring to a section connected to the portal. Then, the centers of the portals on the way from the current position to the destination position are sequentially joined by straight lines, and thereby, the traffic line is set.
Further, there has been proposed a technology of evaluating a spline curve such that pass points set on a two-dimensional image are joined and moving the viewpoint of the walk-through along the evaluated curve (for example, Patent document 2).